Did you have a sudden frost? Otherwise, I don't think cutting it down would solve the problem. You need to find out why it wilted. It could be something noshing at the roots. Try giving it a new home - transplant it to a new location.

do you know which plant it is? That would help us to help you with the problem.

It does look like frost damage followed by sun/wind damage.

you could try cutting it down and see if it re-sprouts from the base.

Could definitely do with knowing what the plant is & how long it's been there?
Bathgate's right though, lift it out gently with as much of it's roots as possible. Check that the roots aren't rotting/being eaten & make sure they're not all knotted together. Check in the hole for anything that might've caused it. Is the soil too dry or wet? That sort of thing...

A close-up photo of a green bit might help id it if you're not sure what the plant is

i wouldnt lift it if it has been in the ground for several years especially as the weather warms up the roots will be compromised. until we know what it is and how long its been in etc there is not much we can suggest.
prune away the brown leaves to improve its appearance if you want to.

Agree with Seaburngirl's comment wholeheartedly - that looks like a reasonably big plant, and not something that's been shoved in recently... but impossible to tell what it is, its blurry under magnification. Likely its something that came into growth too early owing to the almost summery February, then got blasted by the drop in temperatures during March and April, not an uncommon event for a lot of plants this year.

Thanks everyone for your comment, the plant is call Choisya ternate, DarrenB and it was over 11 years as it was planted from previous owner, how long before I havn't got a clue. Seaburngirl hope this also answer your questions and maybe due to weather too, I had already cut off the brown side on one half of the bushes. I think in May will see whether any hope if not time to chop it down. Much appreciated all your advise.

If its Choisya ternata, the damage is unlikely to have been caused by the weather, some other problem is obviously going on, maybe something at the root. Cut it down to about 6 inches either now or at the beginning of May, give a handful or two of Growmore or similar raked in at the base, and see if it regrows healthily or not.

Thanks Bamboo, I already given some Growmore around the root but havnt cut it down will it and hope it start again.